The issue of adding fluxes to coal quality
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Is there any basis for the principle mentioned in a technical report, which states that limestone present in raw coal can be partially decomposed to produce CO2, which in turn is converted into CO thereby increasing the amount of useful gas in the coal gas?
Thinking in this way is a bit far-fetched; when it comes to fluxes, the amount of limestone used is very small, and the decomposition temperature is high.
If it is raw coal with a ash fusion point of 1500 degrees, should the amount of flux to be added be calculated based on a level of 7%?
The decomposition temperature of limestone is around 900°C. Assuming a coal feeding rate of 50 tons/h, the amount of limestone added is 3.5 tons/h; as a result, the CO2 generation rate is less than 800 Nm3/h. This amount is negligible compared to the effective gas volume of tens of thousands of cubic meters, and can be ignored
For example, adding 2.7 tons of limestone per hour can result in 720 cubic meters of CO2 being produced; this volume is negligible compared to tens of thousands of cubic meters of dry gas.
Adding limestone as a cosolvent to the raw coal is intended to lower the ash melting point; this in turn reduces the operating temperature, decreases heat loss, and increases the concentration of useful gas components.
There is no basis for it. On the contrary, adding it corresponds to an increase in the ash content, resulting in an increase in the CO2 content in the syngas.